Semiconductor internal combustion engine ignition system



R. L. KONOPA May 10, 1966 SEMICONDUCTOR INTERNAL COMBUSTION ENGINE IGNITION SYSTEM Filed Dec. 20, 1963 INVENTOR R/CHA RD L. KO/VOPA BY c -R m ATTORNEY United States Patent O 3 250 954 SEMICONDUCTOR iN'riznNAL COMBUSTION ENGINE IGNITION SYSTEM Richard L. Konopa, Anderson, Ind, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Dec. 20, 1963, Ser. No. 332,054

3 Claims. (Cl. 315-209) This invention relates to ignition systems for an internal combustion engine and more particularly to a semiconductor ignition system which is capable of controlling the current fiow through the primary winding of an ignition coil.

The present invention is concerned with an ignition system which in its broadest aspect is of a type shown in the patent to Konopa, 3,087,098, and in the patent to Short et al. 3,087,001.

One of the objects of this invention is to provide a transistor ignition system which has an improved performance at low engine speeds.

Another object of this invention is to provide a transistor ignition system which is of the breakerless type and which requires less output voltage from a pick-up coil as compared to heretofore known systems.

Still another object of this invention is to provide a transistor ignition system wherein switching of the system from one condition to another is accomplished by a circuit that includes a Zener diode.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiment of the present invention are clearly shown.

The single figure drawing is a schematic circuit diagram of an ignition system made in accordance with this invention.

Referring now to the drawing, the reference numeral designates a source of direct current which in this case, is shown as a battery. The voltage of the source 10 is impressed across power conductors 12 and 14 whenever the ignition switch 16 is closed. The source of direct current could also be a generator which is used, for example, on motor vehicles to charge the battery under certain conditions of operation. It is noted that conductor 14 is grounded.

The reference numeral 18 designates an internal combustion engine which has a plurality of spark plugs 20.

The spark plugs are fed by spark plug wires 22 which are connected with the inserts or electrodes 24 of a distributor cap 26 that is formed of insulating material. The electrodes 24 cooperate with a rotor contact 28 which is driven by the engine 18 as is apparent from the dotted line representation on the drawing. The rotatable rotor contact 28 is electrically connected with a conductor 30 which feeds a high voltage to the spark plugs via the rotor contact 28, electrodes 24 and conductors 22.

The device for timing the spark plug impulses is a pulse generator designated in its entirety by reference numeral 32., This pulse generator includes a rotor 34 which is formed of magnetic material and which has four pole tips that cooperate with a U-shaped magnetic part 36. The flux that passes through the magnetic circuit of the part is generated by a permanent magnet 38 and it is seen that a pick-up coil 40 is wound on the U-shaped part. The rotor 34 is driven by the engine 18 and is synchronized in its rotation with rotor contact 28. If desired, the magnetic pick-up 32, the distributor cap 26 and the rotor contact 28 can be built into one unit.

It will be appreciated that as the rotor 34 rotates, the flux flow through the magnetic part 36 is closed and 3,250,954 Patented May 10, 1966 interrupted and therefore a train of voltage pulses is induced in the pick-up 40. The flux path is completed when the pole tips of rotor 34 are in the position shown in the drawing and is interrupted when the pole tips move out of alignment with the ends of part 36. These voltage pulses have a predetermined time spacing and the arrangement is such that at times there is no voltage developed in pick-up coil 40 and at other times, voltage pulses are present. The frequency of the voltage pulses depends upon the speed of the engine 18.

The spark impulses that are supplied to conductor 30 come from a secondary winding 42 of an ignition transformer 44. This ignition transformer has a primary winding 46.

The primary and secondary windings of the ignition transformer are connected together at junction 48 and this junction is connected with the positive power conductor 12. The opposite side of the primary winding 46 is connected with the collector of an NPN transistor 50. The emitter of transistor 50 is connected with the grounded power conductor 14.

The base of transistor 50 is connected with a junction 52. A resistor 54 connects the power conductor 14 and the junction 52. The junction 52 is connected with the emitter of another NPN transistor 56. A resistor 58 connects the collector of transistor 56 and the power conductor 12.

The ignition system has another NPN transistor 60. The collector of transistor 60 is connected with junction 62. A Zener diode 64 is connected between junction 62 and the base electrode of transistor 56. The Zener diode has the characteristic of preventing current flow between junction 62 and the base of transistor 56 untl a predetermined voltage is applied across it'whereupon the Zener diode will break down and conduct.

The junction 62 is connected with conductor 12 through a resistor 66. The emitter of transistor 60 is connected to the grounded conductor 14 by a conductor 68.

The base of transistor 60 is connected with junction 70. A resistor 72 is connected between junction 70 and the conductor 12. The pick-up coil 40 of the magnetic pick-up 32 is connected between junction 70 and the power conductor 14.

When the ignition switch 16 is closed, the voltage of the direct current source 10 is impressed across conductors 12 and 14. If the rotor 34 is now rotating due to a cranking of the engine or when the engine is running, the ignition system will be operative.

When there is no pulse of voltage induced in the pick-up coil 40, the transistor 60 is biased to conduct a slight amount between its collector and emitter by the direct current source 10. The junction 62 will now be at a potential which is sufiicient to break down the Zener diode 64 such that current will flow between junction 62 and the base of transistor 56. This will cause the transistor 56 to be biased to a conductve state since it is supplied with base current and the transistor 56 therefore turns on between its collector and emitter. With transistor 56 turned on in its collector to emitter circuit, the junction 52 has a potential which is sutficent to cause the transistor 50 to be biased to a conductive state between its collector and emitter.

When the transistor 50 turns on between its collector mode of operation, the transistor 60 is not fully conductive but only slightly conductive.

When a pulse of voltage of the correct polarity is induced in the pick-up coil 40, the potential of junction 70 increases in a positive direction to drive the transistor 60 from a slightly conductive condition to a substantially fully conductive condition. This reduces the voltage drop across the collector and emitter electrodes of transistor 60 and as a result, the potential of junction 62 will be lowered. The potential of junction 62 is lowered to a point where the Zener diode reverts back to its blocking condition and the base current for transistor 56 is theretore cut off. Since the base current for transistor 56 is cut off, this transistor will switch off in its collectoremitter circuit and no base current will therefore flow to the base of transistor 50. The transistor 50 will now shut oil? in its collector-emitter circuit which interrupts current flow through the primary winding 46. This causes a large voltage to be induced in the second winding M which is applied to one of the spark plugs via conductor 30, rotor con-tact 28, one of the electrodes 24, and through one of the spark plug leads 22.

As the voltage induced in pick-up coil varies between a maximum value and zero, the transistor is switched on and off to control the current flow through primary winding 46. When primary Winding current is interrupted, oneof the spark plugs is fired and the rotation of rotor 34 and rotor contact 28 is synchronized so that a spark impulse will be provided when the rotor contact 28 is in alignment with one of the electrodes 24.

While the embodiments of the present invention as herein disclosed, constitute a preferred form, it is to be understood that other .forms might be adopted.

What is claimed is as follows:

1. An ignition system for an internal combustion engine comprising, an ignition coil having a primary Winding and a secondary windings, a source of direct current, first and second conductors connected across said source of direct current, a first transistor, means connecting said first transistor and said primary winding in series cross said conductors, a second transistor connected across said conductors, said second transistor controlling the bias applied to said first transistor, a third transistor having its emitter-collector circuit connected across said conductors, a magnetic pulse generator driven by said engine, said pulse generator having a winding, said winding being connected across the emitter and base electrodes of said third transistor, a resistor connecting the collector of said of said third transistor to one of said conductors, the junction of said resistor and said collector forming a variable potential points, the potential of said variable potential point decreasing when said third transistor is conductive, and a Zener diode connected between said variable potential point and the base electrode of said second transistor, the voltage of said potential point being sulficient to break down said Zener diode and bias second and first transistors to a conductive condition when said ,third transistor is at less than full conduction, the voltage of said potential point being lowered when the conduction of said third transistor is increased, said voltage having a value that is not sufiicient to break down said Zener diode when the conduction of said third transistor is increased whereby said second and first transistors are biased nonconductive.

2. A transistor ignition system comprising, a source of direct current, first and second conductors connected across said source of direct current, an ignition coil having a primary winding and a second winding, a magnetic pulse generator including a coil winding, said magnetic pulse generator being driven in synchronism with said engine, first, second and third transistors each having emitter, collector and base electrodes, means connecting the emitter and collector of said first transistor in series with said primary winding across said conductors, a first circuit connecting the emitter and collector of said second transistor across said conductors, means coupling said first and second transistors whereby said second transistor controls the conduction of said first transistor, a second circuit connecting the emitter and collector of said third transistor across said conductors, a third circuit connected across said conductors including said coil winding and a resistor, said coil winding and resistor having a common junction, means connecting the base of said third transistor with said junction and a Zener diode connected between the collector of said third transistor and the base of said second transistor, said Zener diode being biased conductive to bias said first and second transistors conductive when the conduction of said third transistor is decreased to a predetermined value said Zener diode being biased nonconductive when said third transistor is biased substantially fully conductive to bias said first and second transistors nonconductive.

3. A transistor ignition system comprising, an ignition coil having a primary winding and a secondary winding, a magnetic pulse generator including a coil winding, said pulse generator being driven in synchronism with said engine, first and second conductors adapted to be connected across a source of direct current, first, second and third transistors each having emitter, collector and base electrodes, means connecting the emitter and collector of said first transistor and said primary winding across said conductors, :means connecting the emitter and collector of said second transistor across said conductors, means connecting the emitter of said second transistor to the base of said first transistor, a circuit connecting the emitter and collector of said third transistor across said conductors, a Zener diode connected between the collector of said third transistor and the base of said second transistor, a first resistor connected between one of said conductors and said collector of said third transistor, a circuit connected across said conductors including .a second resistor and said coi-l winding, said second resistor and coil winding having a common junction connected with the base of said third transistor, said Zener diode being conductive when said third transistor is conducting at a point less than its full conduction and being biased nonconductive by the voltage drop across said first resistor when said third transistor is substantially fully conductive.

References Cited by the Examiner UNITED STATES PATENTS 2,964,653 12/1960 Cagle et a1. 307-.88.5

I FOREIGN PATENTS 861,534 2/1961 Great Britain.

JOHN W. HUCKERT, Primary Examiner.

DAVID J. GALVIN, Examiner.

A. I. JAMES, Assistant Examiner. 

1. AN IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING, AN IGNITION COIL HAVING A PRIMARY WINDING AND A SECONDARY WINDINGS, A SOURCE OF DIRECT CURRENT, FIRST AND SECOND CONDUCTORS CONNECTED ACROSS SAID SOURCE OF DIRECT CURRENT, A FIRST TRANSISTOR, MEANS CONNECTING SAID FIRST TRANSISTOR AND SAID PRIMARY WINDING IN SERIES CROSS SAID CONDUCTORS, A SECOND TRANSISTOR CONNECTED ACROSS SAID CONDUCTORS, SAID SECOND TRANSISTOR CONTROLLING THE BIAS APPLLIED TO SAID FIRST TRANSISTOR, A THIRD TRANSISTOR HAVING ITS EMITTER-COLLECTOR CIRCUIT CONNECTED ACROSS SAID CONDUCTORS, A MAGNETIC PULSE GENERATOR DRIVEN BY SAID ENGINE, SAID PULSE GENERATOR HAVING A WINDING, SAID WINDING BEING CONNECTED ACROSS THE EMITTER AND BASE ELECTRODES OF SAID THRID TRANSISTORS, A RESISTOR CONNECTING THE COLLECTOR OF SAID OF THE THIRD TRANSISTOR TO ONE OF SAID CONDUCTORS, THE JUNCTION OF SAID RESISTOR AND SAID COLLECTOR FORMING A VARIABLE POTENTIAL POINTS, THE POTENTIAL OF SAID VARIABLE PORTENTIAL POINT DECREASING WHEN SAID THRID TRANSISTOR IS CONDUCTIVE, AND A ZENER DIODE CONNECTED BETWEEN SAID VARIABLE POTENTIAL POINT AND THE BASE ELECTRODE OF SAID SECOND TRANSISTOR, THE VOLTAGE OF SAID POTENTIAL POINT BEING SUFFICIENT TO BREAK DOWN SAID ZENER DIODE AND BIAS SECOND AND FIRST TRANSISTORS TO A CONDUCTIVE CONDITION WHEN SAID THRID TRANSISTORS IS AT LESS THAN FULL CONDUCTION, THE VOLTAGE OF SAID POTENTIAL POINT BEING LOWERED WHEN THE CONDUCTION OF SAID THRID TRANSISTOR IS INCREASED, SAID VOLTAGE HAVING A VALUE THAT IS NOT SUFFICIENT TO BREAK DOWN SAID ZENER DIODE WHEN THE CONDUCTION OF SAID THIRD TRANSISTOR IS INCREASED WHEREBY SAID SECOND AND FIRST TRANSISTORS ARE BIASED NONCONDUCTIVE. 